Estuarine oceanography of the Vembanad lake Part II : the region between Cochin and Azhikode

Some aspects of the estuarine oceanography of the Vembanad lake between Cochin and Azhikode are discussed. Since this part of the lake is in confluence with the Arabian sea at its southern and northern ends, at Cochin and Azhikode, its circulation pattern and other characteristics are different from what they are between Cochin and Vaikom. Because of the position of these two mouths, which are exposed to the same tidal cycles, the high tides and low tides each producing two opposite flows respectively converge and diverge leaving a null zone, almost free of the tidal effect, around Kadakara, situated midway between Cochin and Azhikode. Another significant feature of this pairt of the estuary is an extreme low-salinity i«gion between Karthedam and Cherai during monsoon and early postmonsoon, brought about by the deflected waiters of the Periyar, opening at the northern end of the estuary

Design of Routers for Optical Burst Switched Networks

Optical Burst Switching (OBS) is an experimental network technology that enables the construction of very high capacity routers using optical data paths and electronic control. In this dissertation, we study the design of network components that are needed to build an OBS network. Specifically, we study the design of the switches that form the optical data path through the network. An OBS network that switches data across wavelength channels requires wave-length converting switches to construct an OBS router. We study one particular design of wavelength converting switches that uses tunable lasers and wavelength grating routers. This design is interesting because wavelength grating routers are passive devices and are much less complex and hence less expensive than optical crossbars. We show how the routing problem for these switches can be formulated as a combinatorial puzzle or game, in which the design of the game board determines key performance characteristics of the switch. In this disertation, we use this formu-lation to facilitate the design of switches and associated routing strategies with good performance. We then introduce time sliced optical burst switching (TSOBS), a variant of OBS that switches data in the time domain rather that the wavelength domain. This eliminates the need for wavelength converters, the largest single cost component of systems that switch in the wavelength domain. We study the performance of TSOBS networks and discuss various design issues. One of the main components that is needed to build a TSOBS router is an optical time slot interchanger (OTSI). We explore various design options for OTSIs. Finally, we discuss the issues involved in the design of network interfaces that transmit the data from hosts that use legacy protocols into a TSOBS network. Ag-gregation and load balancing are the main issues that determine the performance of a TSOBS network and we develop and evaluate methods for both

Oceanographic features and abundance of the pelagic fisheries along the west coast of India

The results of a study on the hydrographic properties such as temperature, salinity and Sigma-T (density) content of the surface waters along the west coast of India collected during the cruises of R. V. Varum and other vessels are presented e,s an average distrbution of the factors month-wise for each degree square. This has been used to investigate the relationship of the hydrographic conditions with the pelagic fishery landings such as thpsp of the oil sardine and the Indian mackerel month-wise. The importance of the coastal phenomena like upwelling and sinking in relation to the fishery landings is pointed out

Seasonal variations in the hydrographic features Along the southwest coast of India

The seasonal variations of the hydrographic features in a quasimeridional hydrographic section from Cape Comorin to Karwar is presented and discussed. TTie average depth up to which the investigations are extended is 300 metre. The paper embodies data for the period 1957-1967, which have been averaged. Attention is drawn to the latitudinal and bathymetric variation in the hydrographic features

On upwelling along the west coast of India

The Oceanographic features prevailing along the west coast of India from Ratnagiri to Cape Comorin during the monsoon season of 1962 are presented and discussed. Nineteen hydrographic sections were investigated out of which twelve have been taken up for consideration. It was found that upwelling was noticeable to a marked extent in the region Calicut to Karwar and during this period a strong southward flow existed along the west coast. The topography of the bottom of the convection layer was also studied to have additional information regarding the monsoon features. In this connection the associated vertical migration of the thermocline during this period is shown and the probable causes of upwelling along this coast are discussed

Hydrography of the west coast of India during the pre-monsoon period of the year 1962—part 2: in and offshore waters of the Konkan and Malabar coasts

The hydrographic conditions prevailing along the Maharashtra and southwest Saurashtra coasts during the pre-monsoon season of the year 1962, have already been published (Patil et al., 1964). The present paper is a continuation of the same and describes the conditions off the central and southern parts of the west coast viz. the Konkan and Malabar coasts, and presents a pioneer survey of the region north of 13°N latitude along the west coast

Salinity changes in the estuary and the coastal sea adjacent to the portmouth at Cochin

The article deals with the details of salinity changes in the Cochin estuary and its influence and interrelations with the Vembanad lake

Estuarine oceanography of the Vembanad lake Part I: The region between Pallipuram (Vaikom) and Thevara (Cochin)

The paper gives the results pertaining to the region between Pallipuram (Vaikom) and Thevara (Cochin) of a detailed estuarine-oceanographic study attempted on the Vembanad lake from Pallipuram in the south to Azhikode in the north. The study was aimed primarily at classifying to what type of estuary the lake belongs. As the two factors almost equally influencing the lake, namely the incursion of salt water from the Arabian sea and fresh water from the rivers, both being by far governed by the monsoon, the major classification was attempted on a seasonal basis

Hydrography of the waters along the Gujarat Coast during the summer period of the year 1963

The hydrographic features of the waters along the Gujarat Coast during the summer period of 1963 are presented and discussed. During this period the waters were mostly isothermal within the continental shelf and a thermocline was perceptible only outside the shelf. Maximum salinity was observed in the region off Porbandar which again was the region of minimum temperature and maximum dissolved oxygen content. A southward increase in temperature was associated with a southward decrease in salinity. The sinking and spreading of high saline waters from the Gulf of Aden and Persian Gulf were perceptible in investigational area

Estuarine oceanography of the Vembanad lake Part iii: the region between Cochin and The 30 m depth off port mouth

The time-distribution patterns of temperature, salinity and oxygen content along the shipping channel from inside the port to a distance of about 15 km out into the Arabian sea during 1981-1983 are presented and discussed in this third and last part of the estuarine oceanographic study of the Vembanad lake. The distribution patterns show that hydrologically the nearshore region up to 12 or 15 km off Cochin is more or less identical to the adjacent coastal region, without having any apparent influence of the lake, during the dry months January to May. During the wet months, however, the discharge from the lake, characterized by suspended sediments, spreads as a plume, over highly saline and cold upwelled water, turning the region into an intermittent estuary. Though the end of the plume can often be pinpointed around the 30in depthline, by a sharp change of colour and filaments formed of floating objects of land and freshwater origin, the presence of an actual plume front is doubtful because of the weak surface convergence then occurring in a broad area off Cochin